Submarine sound producer



Dec. 21 1926.

v 1,61 1,740 w. HAHNEMANN SUBMARINE SOUND PRODUCER Filed Jan. 6, 1921 2 Sheets-$heet 1 W. HAHNEMANN SUBMARINE SOUND PRODUCER Dec. 21 1926. 1,611,740

Filed Jan. 6, 1921 2 Sheet s-Sheet 2 Patented i USSIA, ASSIGNOR TO THE iarEL, GERMANY.

SUBMARIHE fiQUhl'D PRODUCE}.

Application filed January 6, 1921, Serial No.

V This invention relates to closed sound producers that are adapted to be submerged and intended to be used for propagating sounds for short distances, as a means for testing submarine sound signal receivers, as well as for sending out sound signals over long distances as a means of navigation, or for indicating the safe course for ships, etc.

The sound senders or producers hitherto used for this purpose generally consisted oi a structure more or less similar to a bell in shape that was struck under water by a bell hammer driven by a striking mechanism. These senders were made either in the form 5 of an open mouthed bell with a hammer moved in the water through the agency of an element passed through an opening with water-excluding: packing into a chamber that contained the driving mechanism. or in the shape of a closed sound radiating; body, or part on. it. in whose interior a. hammer was placed.

Sound emitting bodies of this kind are very unsatisfactory, especially in regard to their acoustic properties. The bell-like body excited by the stroke has to perform both of two distinct functions at the same time,'viz, that of taking up the vibratory force imparted to it' by the hammer or exciting agency, and that of giving out or radiating the sound vibrations into the abutting; water. This makes it impossible to obtain the most favorable damping; conditions for sound radiation, and at the same time to produce a soupd sender whose radiating properties and efiiciency reach a high level. p

The aforesaid drawbacks are avoided by the present invention which consists. in the first place, in connecting' a special vibratory structure to the sound radiating; member abutting against the water, in order to obtain the most favorable damping conditions for radiation that the requirements to be met by the apparatus will permit, and in order to put the radiating properties or the efliciency of the apparatus up to the highest possible figure. Besides, according to the invention, a portion of the wall of the closed watertight casing is arranged to act as the sound radiator and cooperates with the special vibratory structure, and a self-acting striking or exciting mechanism is arranged in the casing. Any form of energy, such as mechanical, electrical or pneumatic en- 435506, and in Germany February E3, 1914-.

erg-y, etc., may be employed for driving the self-acting striking mechanism. All the parts of the apparatus are contained within the watertight casing, so that they operate free from the sound propagating liquid the object of this being to eliminate the usual moving parts passing from the operating mechanism through the walls of the casing; into the outer water which require special packing means to make the chamber watertight at that point.

A sound producer thus constructed inaccordance with the invention offers the advantage over known devices that, inaddi tion to the avoidance of packing or sealing; means in the openings through which mov ing parts extend into the water-tight char her, the arrangement of a portion of the wall of the casing as a sound radiator permits oi the production of apparatus on a large scale in which distinctand equal tuning and;

damping of all apparatus of one and the same type can be obtained. Besides, the provision of, the special vibratory structure, which stores up the energy delivered to by blows, and gradually transfers this energy to the radiating portion or plate, renders the variability of the tuning and clamping factors of the apparatus much more flexible, so that concordance or any desired relationship can more easily be obtained not only among diiierent sized apparatus of one and the same type, but also amongst apparatus of the various forms of construction described at the beginning of this specification.

Hence the predetermination by calculation Fig. 2 is a vertical section on a plane at rightangles to that of Fig. .1.

Fig. 8 lllustrates a long-range soundproducer with a partlcularly eiiectlve form oi.

vibrating structure andv radiating member.

In the sound producer shown in 1 a vibratory structure in the shape of a tuning fork 3 co-operates with a thin vibratingwall 1 of the casing 2. In the casing 2, which is composed of two halves, whose joint is made water-tight by a gasket of round cross-sectron, a clockwork t is arranged which operates to revolve a pm 6 that forces back a cam lever 7 and a hammer attached thereto; .By

this meansan adjustable spring 8 is torn sioned which jerks the'hamn'ier against the tuning fork. This latter is provided with sliding weights 9 by which its tone can be adjusted to ditlierent pitches.

The clockwork is wound upby means of a winding pin 10 and it is arranged so that the intervals at which it causes the hammer to strike the fork can be adjusted.

The constructional form shown is arranged to be wound by a key inserted -from without, so that no removal of the upper part of the casing is necessary. To this end an opening or eye 11,. which is in line with the winding pin 10, is provided in the casing 2. The eye is closed by a cap 12' which has a knob in which a spindle 13 is fixed that is used for winding up the ClOCliWOl'l. To perform the winding operation it is only necessary .to unscrew the cap 12 and thrust the spindle through the hole or barrel in the eye 11 until the end of the spindle seizes the winding pin 10. A disk of packing substance is placed at the bottom of the pit in the cap in order to ensure a water-tight closure when the cap is screwed fast. The winding spindle fixed in the cap afiords a ready means for screwing the cap down tight enough. The horizontal vibrations of the prongs of the fork are accompanied by vertical vibrations of the stem of the fork and thus the thin bottom or radiating member 1 of the sound producer is caused to send out sound waves.

Fixed to the top of the casing is a ring it by which the apparatus may be suspended and let down into the water, as over a ships side. As stated above this device is intended for sending sound over short distances.

Another arrangement which is also suitable for obtaining excellent results in sinnalling over long distances comprises a vibratory structure enclosed in the casing and constructed so that its principal vibrating mass and its elastic force. reside in portions of its body which are practically distinct from one another.

i A constructional form of a sound producer of this category is shown in 8.

A helmet shaped vessel 15 is closed at one end by a sound radiating plate 16.v Attached to the inner surface of the radiator 16 is a vibratory structure whose vibrating masses reside chiefly in the weights 17 and 1S, and whose elastic forces reside principally in the springs 19 and 20. A hammer 21 that is actuated by pneumatic driving device 22 acts upon the weight 18 and thus excites the entire vibratory structure.

It will be observed that the mass 18 is smaller than the effective mass at- 17. In a vibratory structure such as shown this difference in size will cause: the mass 18 to eXecutc larger amplitudes of movement than mass 11,. which is highly desirable in submarine signaling.

The various parts ofthe apparatus may be designed in any approved manner. The striking mechanism in particular may be driven by mechanical, hydraulic or electric driving means.

The tuning of the part of the casing that acts as the radiating member or the sound producer may be arranged to stand insome defined relation to the vibratory structure attached to it, so that certain coupling etliects will result which it is possible to predetermine. Thus, while giving due consideration to the mutual eifects that the masses of the radiating member and the vibratory structure exert upon each other, an individual tuning of each of these parts tothe same frequency may be effected. But on the other hand the tuning; of the radiating member may be made to differ widely from that of the vibratory structure coupled with it. Thus the note of the radiating member may be made so much lower than that of the vibratory structure that the former is compelled to execute the same vibrations as or is dominated by the latter. If the latter course, i. e. the positive control of the radiating member by the vibratory structure,

is adopted, it will be advantageous to arrange the radiating member in such a man ner that it executes a certain form of oscillation; for example, so that bulges are formed by its entire surface in oscillating which corresponds in shape to its fundamental vibrations, or so that an annular portion of it situated between slightly oscillating central and peripheral zones executes vibrations of large amplitudes. If the radiating member is a diaphragm this may be accomplished by providing it with special stiffening members, such as ribs or the like. The entire surface may be caused to bulge as a whole in the described manner by attaching stiffening ribs to the diaphragm that extend from its centre to its periphery, and large amplitudes of an annular portion I the diaphragm may be brought about by thickening the annular portion that extends round the centre of the diaphragm, about half way between the centre and the periphery.

sound radiating portion and the other mass mass is smaller than the other mass of the being freely vibratory and striking means vibratory structure. for striking said freely vibratory mass to ex- 3; A submarine sound producer accordcite said vibratory structure; the striking ing to claim 1, in Whichthe striking means 5 means and the vibratory structure being is a pneumatic hammer.

contained entirely Within the casing. In testimony whereof I affix my signature;

2. A submarine sound producer according to claim 1, in Which the freely vibratory WALTER HAHNEMANN. 

